高铝钢连铸结晶器保护渣热力学行为及过程数学模拟

Continuous casting of high aluminum steel has become a hot spot in high value-added products with proprietary IPR, which countries and steel works are all competing for. The mold flux is likely to be reduced by aluminum during high aluminum steel continuous casting, which would cause major variation in concentrations and the properties of molten mold flux. It would also lead to slab quality defects of continuous casting billet. Thus, how to protect the mold flux from being reduced by Al in molten steel, or to reduce its effects on molten mold flux as little as possible is the key problem. And it is up to the critical content of reactive components in flux. Firstly, the critical content is determined by the equilibrium concentration of the reaction at the interface between the molten mold flux and the molten steel, that is, it depends on the activity of the compositions in the molten mold flux. Secondly, it is also related to kinetic factors such as reaction rate and time. Present project intends to focus on the critical content. Thus, the project starts from the thermodynamics and kinetics mathematical modeling of simultaneous reaction for multi-component system. And the equilibrium concentration of the components will be determined based on the studies on thermodynamic behavior such as the activity and the solubility of components participated in the reduction reaction. Then get the equilibrium relationship between the concentration of components in molten mold flux and the aluminum in molten metal. The nature and the variation law of thermodynamics and kinetic of simultaneous chemical reaction in multi-component system during continuous steel casting of high aluminum steel will be investigated. Thus, a critical concentration which the physicochemical property of mold flux doesn’t vary much when the components are reduced by aluminum in molten metal is put forward. The variation of components in molten mold flux during continuous casting of high aluminum steel will be predicted. The formulating of recipe in mold flux for high aluminum steel and the optimization of process parameters for continuous casting of high aluminum steel will be done. This project will not only provide important theoretical basis for formulation design and application of the continuous casting mold flux, but also have important practical significance on guiding casting process for high aluminum steel, which would be a break through on the production bottleneck of high aluminum steel continuous casting.

高铝钢连铸是各厂各国争夺高附加值产品自主知识产权的热点。高铝钢连铸中现有保护渣易被铝还原，造成成分巨变，引起渣性能巨变，使连铸中断，产生铸坯质量缺陷。本项目拟围绕高铝钢连铸结晶器保护渣中反应性组分的“临界”含量，从化学反应热力学和多组分体系同时反应动力学数学模拟角度展开研究。研究参与反应的渣中组分活度系数及其与各组分浓度间的关系，从而确定其平衡浓度，获得渣中组分浓度与钢液中铝含量间的热力学平衡关系；研究连铸过程中在结晶器内的钢水和熔渣中组分浓度随时间的变化，以揭示结晶器内反应的热力学和动力学本质和规律。最终提出保护渣中组分纵使被还原但对渣性能影响不大的临界含量，预报高铝钢连铸过程中结晶器内保护渣成分的变化规律，优化保护渣配方设计和连铸工艺参数，为连铸结晶器保护渣的配方设计、研制及其应用提供重要理论依据，对突破高铝钢连铸生产的瓶颈，确定连铸关键工艺参数，指导和优化高铝钢连铸工艺有重要的意义。

高铝钢连铸是各厂各国争夺高附加值产品自主知识产权的热点。高铝钢连铸中现有保护渣易被铝还原，造成成分剧变，引起渣性能剧变，使连铸中断，产生铸坯质量缺陷。本项目围绕高铝钢连铸结晶器保护渣中反应性组分的“临界”含量，从化学反应热力学和多组分体系同时反应动力学数学模拟角度展开研究。研究参与反应的渣中组分活度系数及其与各组分浓度和碱度间的关系，从而获得渣中组分浓度与钢液中铝含量间的热力学平衡关系；研究连铸过程中在结晶器内的钢水和熔渣中组分浓度随时间的变化，以揭示结晶器内反应的热力学和动力学本质和规律。最终提出保护渣中组分纵使被还原但对渣性能影响不大的临界含量，预报高铝钢连铸过程中结晶器内保护渣成分的变化规律，优化保护渣配方设计和连铸工艺参数。项目获得了以下重要研究成果：（1）测得了CaO-SiO2-Al2O3-MgO-MnO基高铝钢连铸结晶器保护渣及其加入B2O3和CaF2渣系中SiO2、Al2O3、B2O3及MnO在1450℃下的活度系数，提出了这些组分的活度系数与渣中SiO2、Al2O3、B2O3、CaF2浓度及碱度间的二次回归关系式。为研究和控制高铝钢连铸过程中的反应提供基础的热力学数据，拓展了冶金热力学数据库。（2）提出了高铝钢连铸过程中发生的铝还原渣中SiO2、B2O3和MnO反应在1450℃下在不同铝量时达到平衡的SiO2-Al2O3、B2O3-Al2O3和MnO-Al2O3间的平衡关系。为高铝钢连铸结晶器保护渣的成分设计和研制提供了理论依据。（3）提出了考虑渣中Si-O复杂阴离子存在的改进的分子-离子共存模型，并用于CaO-SiO2-Al2O3-MgO-MnO、CaO-SiO2-Al2O3-MgO-MnO-CaF2及CaO-MgO-MnO-FeO-SiO2渣系中组分活度的计算。为研究和控制高铝钢连铸过程中的反应提供了理论依据，进一步拓展了冶金热力学数据库。（4）提出了高铝钢连铸过程中结晶器内的多组分反应体系同时反应动力学模型。预报了连铸中钢、渣中成分的变化，为指导连铸生产、连铸工艺的优化及保护渣的成分设计和研制提供理论指导。（5）已发表7篇研究论文，其中SCI和EI收录5篇。已授权国家发明专利2项，公开2项。国内、国际会议口头报告3人次。培养硕士研究生5人，已取得硕士学位3人，在读2人。项目投入总经费61万元，总支出57.9602万元，剩余经费2.7838万元。